An Analysis of Local Tie Vectors’ Temporal Evolution and Site Stability at Medicina Observatory through Terrestrial and GPS-based Observations

The observatory of Medicina (Italy) hosts a co-location between GPS and VLBI, whose eccentricity vector has been re-measured several times once since 2001. As a result, the co-located site is now provided with a series of nearly annual local tie vectors produced by means of terrestrial and GPS-based observations. This work aims at summarising the results of a systematic analysis of the whole set of local ties produced so far and highlighting at the same time their temporal evolution. As such, the application of algebraic tools focussed on deformation detections can benefit the analysis of the local tie temporal variations and at the same time that one of the “geodynamical” stability of the co-located site. Nevertheless, just like in any other problem of deformation detection, such an analysis would ask for a reproducible local datum, according to which the relative displacements among the points have to be referred to. The application of algebraic projection theory to the local tie oriented-networks will be carried out in order to select a “common and fully reproducible” datum onto which the network solutions will be projected and discuss possible displacements within the re-measured networks.